Multicomponent gas chromatographic analysis of urinary steroids excreted by an infant with a defect in aldosterone biosynthesis

The urinary steroids excreted by an infant with a salt-wasting syndrome due to a suspected defect in the 18-oxidation of corticosterone have been analysed by gas chromatography-mass spectrometry. The excretion of tetrahydroaldosterone was low (3.5 μg/24 h) whilst the excretion of 3α, 11β,21-trihydroxy-5α-pregnan-20-one (allo-tetrahydrocorticosterone) and other corticosterone metabolites was high (total about 2 mg/24 h). The excretion of cortisol metabolites was apparently normal for age (total about 2 mg/24 h) but 3α,11β,17α,21-tetrahydroxy-5α-pregnan-20-one (allo-tetrahydrocortisol) rather than tetrahydrocortisone, was the major component of the group. The excretion of an 18-hydroxycorticosterone metabolite 3α,18,21-trihydroxy-5β-pregnane-1 1,20-dione (18-hydroxytetrahydroCompound A) was higher than normal for infants of this age (between 50 and 200 μg/24 h), suggesting that the defect was in 18-hydroxysteroid dehydrogenase rather than 18-hydroxylase. In addition, 18-hydroxytetrahydrocorticosterone, another metabolite of 18-hydroxycorticosterone was tentatively identified and it was found that the rate of excretion of this compound was of similar magnitude to 18-hydroxytetrahydroCompound A. The salt balance of the infant has been successfully controlled by salt administration (77 mEq./24 h) and treatment with Fludrocortisone (0.5 mg/day).